Such an apparatus for manufacturing reinforced hoses as above described was already filed for patent by the applicant of this invention and therefore known (refer to Japanese patent laid-open No. 51-79187). The apparatus for manufacturing reinforced hoses in known art is intended to manufacture a reinforced hose with a reinforcing layer of stranded structure, and the inventors tried to apply it for manufacturing a reinforced hose with a reinforcing layer of spiral structure. In this case, spiral structure means that seen in a reinforcing layer B as shown in FIG. 6 wherein inner reinforcing thread F1 and outer reinforcing thread F2 of plural numbers respectively are wound in spiral on an inner tube 6 in opposite directions with each other.
When the reinforcing layer of spiral structure is formed on the extruded inner tube, however, since the spiral device as a reinforcing layer forming device is usually rotated at such a high speed as 180.about.200 rpm (at a stranding machine, usually 30.about.55 rpm), overrunning of the reinforcing thread on account of the centrifugal force, interference of the top end of the inner die with the reinforcing thread, contacting between the inner and outer reinforcing threads, vibration transmitted from the extruder or the bobbin carrier to the thread and the like cause dispersion in the winding state of the reinforcing thread, thereby it is difficult to obtain uniform spiral structure stably, that is, to obtain a reinforced hose having stable quality (particularly being excellent in high-pressure resistance).
In view of above described aspects, an object of this invention is to provide an apparatus for manufacturing reinforced hoses, in which a reinforcing layer of uniform spiral structure can be formed stably.